1. Field of the Invention
The present invention relates to an electric power unit and an electronics device, more specifically to an electric power unit and an electronics device in which of a plurality of attachable and detachable electric sources by accurately discriminating which of electric sources are mounted, thereby electric supply can be achieved safely.
2. Description of Related Art
Recently, in an electronic device such as a digital camera or the like, there have been used selectively a plurality of electric sources in which various batteries and AC power supplies are converted in DC by an adapter.
For an electronic device which uses a plurality of electric sources, a size AA type-alkali manganese battery as a primary battery and a secondary battery such as a chargeable Ni-Cd (Nickel Cadmium) battery or lithium battery, for example, and so on can be often used. In the electronic device usable the plurality of electric sources in this way, discriminating a kind of the used electric sources is required to utilize a performance of the used electric sources adequately and prevent generation of accidents such as smoking, ignition, explosion or the like.
Therefore, conventionally, there has been proposed an electronic device usable plural kinds of batteries selectively having a means for discriminating kinds of batteries used, and a means for switching supplied currents of the batteries in accordance with discriminated results of the discriminating means (for reference, see JP H 11-84462 A).
Moreover, conventionally, there has been proposed a camera for displaying a loading state by discriminating which of batteries is loaded when one battery which is the same as the other batteries in outer shape, while has different electric characteristic is selected and contained in a battery storage chamber (for reference, see JP 2000-19595 A).
The Applicant has proposed previously an electronic device (for reference, see JP H 7-59335 A) in which an electric source-storage portion and an input terminal for a direct-current power source are provided, either a battery electric source configured to assemble a battery or an AC adapter for converting a commercial alternating current into a predetermined direct-current voltage can be contained in the electric source-storage portion interchangeably, and the input terminal is not used when the AC adapter is used so that the direct-current power source from the input terminal is not applied to a main circuit.
That is to say, the conventional technology makes it possible to charge the battery even when operating the battery electric source and form an electric power unit which does not occupy a space even when operating the commercial power source, and is structured to prevent malfunction and breaking of the circuit from occurring by a current out of the ordinary being applied from the input terminal when the AC adapter is used.
However, in the above-mentioned conventional arts, discriminating the used electric source of the plurality of electric sources is carried out, but solution at the time the discrimination for the used electric source is incorrect is not considered, an improvement in safety of the electric power unit, in particular, prevention of the accident such as the smoking, ignition and explosion or the like is required.